Seedling Emergence Of Grasses Research Articles

Effects of precipitation variation and trampling disturbance on seedling emergence of annual plants in a semi-arid grassland

Precipitation change and grazing are the main factors influencing vegetation structure and dynamics in semi-arid grassland. However, the effects of precipitation variation and livestock trampling on the seedling emergence patterns of plants remain largely unknown. In this study, an experiment with four gradients of trampling (no-trampling, light, moderate, and heavy) and three precipitation treatments (ambient precipitation, +30% precipitation, and −30% precipitation) was conducted to assess the effects of trampling disturbance and precipitation variation on seedling emergence of annual plants. The results showed that an increase in precipitation significantly improved total seedling emergence by 3.5–3.6 times and seedling density of grasses by more than 4.1 times under trampling conditions, while significantly improving total seedling emergence and density of forbs under no-trampling conditions. Moreover, +30% precipitation significantly improved the seedling proportion of grasses under light, moderate, and heavy trampling, while decreasing the seedling proportion of forbs. Seedling emergence of forbs was more sensitive to trampling disturbance, and seedling emergence of grasses was more sensitive to precipitation changes, especially under trampling conditions. Light and moderate trampling with a +30% precipitation increase promoted seedling emergence of grasses, and no trampling with a +30% precipitation increase improved seedling emergence of forbs. Thus, targeted grazing management measures should be implemented for plant communities dominated by either grasses or forbs under changing precipitation conditions.

Conspecific leaf litter and root competition inhibits shrub emergence in the Patagonian steppe

A critical stage in the establishment of new individuals is seedling emergence and litter is a main factor affecting this stage. Recent research found that adults of Chuquiraga avellanedae are over-dispersed. Among several mechanisms, this pattern might be due to the negative influences of adults on seedlings through root competition. We performed field and glasshouse experiments to evaluate (i) the effects of C. avellanedae leaf litter and root presence on the emergence of conspecific seedlings, and (ii) the effects of leaf litter type (C. avellanedae litter, inert litter, no litter) and seed burial depth (seed at the surface or buried) on the emergence of C. avellanedae and Nassella tenuis (dominant grass) seedlings. The field experiment demonstrated root competition from adult plants on shrub seedlings, reducing seedling emergence. However, the effect of root competition did not differ between microsites (under-shrubs vs. between-shrubs). We dismiss the effect of allelopathy because inert litter (i.e., plastic leaves) had the same negative effect as C. avellanedae litter, indicating a mechanical effect. The glasshouse experiment revealed a species-specific response of seedling emergence. C. avellanedae litter limits the emergence of conspecific seedlings but was neutral with regard to the emergence of grass seedlings (N. tenuis). No differences in root competition between microsites and reduction of shrub seedlings by litter suggest that the over-dispersed pattern found for C. avellanedae is caused, at least partially, by litter effects on seedling emergence.

Emergence and Seedling Structure of Temperate Grasses at Different Planting Depths

Some producers have adopted ecologically based practices such as planting complex forage mixtures in their grazing systems to exploit the potential benefits of biodiversity. An understanding of grass seedling emergence and structure under different planting conditions could help develop planting recommendations for establishing multispecies swards. We conducted controlled‐environment and field studies to compare the seedling emergence and morphology of several grasses at three planting depths. Perennial ryegrass (Lolium perenne L.; diploid and tetraploid cultivars), orchardgrass (Dactylis glomerata L.), prairiegrass (Bromus catharticus Vahl), and bromegrass (Bromus stamineus Desv.) were planted at 1, 3, and 6 cm in the growth chamber and greenhouse. Seedlings were destructively sampled 14 d after emergence, and leaves, tillers, and roots were counted. Mesocotyl length and coleoptile width were measured. The grasses were planted in two field experiments to determine emergence and seedling size when planted at 1, 3, or 6 cm. Both perennial ryegrass and orchardgrass elongated the mesocotyl from 1 to 4 cm depending on planting depth, but bromegrass and prairiegrass did not. Seedlings of bromegrass and prairiegrass had greater mass but fewer tillers and roots than perennial ryegrass. Increased planting depth reduced seedling size by reducing the number and size of leaves and number of tillers by 15 to 30% in all grasses. Differences in seedling size and structure among cultivars within species were positively correlated (r of 0.8 to 0.9, P < 0.05) with seed mass. Variation in seed mass and coleoptile width, however, did not explain differences among grasses in seedling emergence in the field.

Evaluation of composts for growth of grass sod

Composts prepared from sewage biosolids-wood chips, mixed municipal solid wastes, autumn leaves, mixed yard wastes, or agricultural wastes were assessed for their effects on growth and composition of perennial ryegrass (Lolium perenne L. ‘Pennfine’). Two biosolids based composts, one mature and one immature, were evaluated. All of the other composts were mature. No supplemental fertilization was provided. Composts were evaluated without amendment or by mixing with soil and sand to create media (proportions by volume) of 100% compost, 90% compost:10% soil-sand, and 75% compost:25% soil-sand. Grass sods were grown in plastic flats in a greenhouse. Quality of sods was assessed by emergence of grass and weeds and by clipping mass in two successive harvests. Macronutrients, micronutrients, and nonessential elements were determined in the grass clippings of each harvest. Grass emergence was lowest in the mixed municipal solid waste compost, which had the highest soluble salt contents of the media. Slight inhibition in grass emergence was noted with the immature biosolids-wood chips compost and the agricultural compost, both of which were nitrogen (N)-rich media. Mean emergence of grass seedlings was increased in all composts, except the yard waste, by additions of sand and soil to dilute the compost. However, emergence of soil-borne weeds lowered the quality of sods as the proportions of soil-sand increased in the media. The principal effects on mass of grass clippings were due to type of compost, harvest, and the interaction of these factors. High N or ammonium restricted the growth in the immature biosolids-woodchips compost, whereas N deficiencies limited growth in the leaf and yard waste composts. Mass of clippings was higher in the second harvest than in the first harvest. Potassium (K) accumulation was low in grass grown in the immature compost, but nutrition with calcium (Ca), magnesium (Mg), and micronutrients was not limiting in any medium. Bioaccumulation of nonessential elements [aluminum (Al), leaf (Pb), cadmium (Cd)] was not apparent. In general, N-rich, well-matured composts were good media for sod growth.

Seedbank Characteristics of a Nebraska Sandhills Prairie

Evaluating seedbank ecology is critical for understanding plant community development and successional patterns and for identifying factors regulating population dynamics. The relationships among seedbank composition, seedbank depth, seed dormancy, and vegetative expression were evaluated for a range site on a Valentine fine sand soil (mixed, mesic Typic Ustipsamments) in the Sandhii Prairie. Twenty soil samples were collected at each of 2 depths (0 to 515 to 20 cm) in early June 1990 and 1991 from 12 macroplots (32 X 32 m) representing 3 range condition classes. A seed extraction and germination trial was conducted to determine the diversity, size, and germinability of the persistent seedbank. Seedling emergence was counted in a greenhouse, with and without a 1Cday prechilling(3 to 5°C) stratification treatment, to characterize seedbank dormancy. Fourteen grass species, 17 forb species, and Schweinitz flatsedge (Cyperus schweinitzii Torr.) were identified in the seed hank. Two additional genera (Carex and Euphorbia) also occurred in the seedbank. Only 10 species occurred in 8 or more macroplots in both years. Aboveground botanical composition was not correlated with (P > 0.10) seedbank species composition. More germinable seeds occurred in the 0 to 5 cm depth (P < 0.01) than the 15 to 20 cm depth. Also, the species diversity and seed number were greater in the shallower depth. Germination percentage was low for all types of vegetation. Lambsquarters (Chenopodiutn album L.) and annual eriogonum (Eriogonum annuum Nutt.) had the largest seedbanks, but germination was less than 6 % . Sand dropseed [Sporobolus cryptandrus (Torr.) Gray] and sand lovegrass [Eragrostis trichodes (Nutt.) Wood] were the most abundant perennial grasses and accounted for about 60% of the germinated seeds. Prechilling increased seedling emergence of grasses (P < O.Ol), forbs (P < O.Ol), and grass-like species (P < 0.01). Perennial grasses emerged first, forbs later, and grasslike species exhibited a bimodal emergence pattern. Based on germination percentage and emergence data, sand dropseed has the potential to colonize openings in the Sandbills prairie, possibly to the exclusion of many annuals occurring in the seedbank.

Influence of Seedbed Microsite Characteristics on Grass Seedling Emergence

Successful germination and establishment of grass seedlings from surface-sown seeds requires a microsite which provides adequate soil water and temperature conditions, among other species-specific requirements. The microsite where these requirements are met has been termed a safesite. Safesites may occur naturally as cracks and depressions in the soil surface, gravel, and plant litter, or be prepared by seedbed equipment and livestock trampling. A greenhouse study was conducted to determine the influence of seedbed microsite characteristics and soil water treatments on seedling emergence of 'Vaughn' sideoats grama (Bouteloua curtipendula (Michx.) Torr.), 'A-130' blue panic (Panicum antidotale Retz.), and 'Cochise' Atherstone lovegrass (Eragrostis lehmanniana Nees X E. tricophera Coss and Dur.). Although there were several interactions, in general, emergence of all 3 species was highest from gravel, followed by litter, cracks, and finally the bare soil surface. Bare surface sites decreased in water content more quickly than the other sites. Cochise lovegrass had high emergence in gravel under all water treatments. Small-seeded species such as Cochise lovegrass broadcast on coarse-textured surface soils may establish with minimal seedbed preparation, provided summer precipitation is adequate.

Effects of Cattle Trampling and Mechanical Seedbed Preparation on Grass Seedling Emergence

Cattle trampling has been recommended to bury seeds and encourage seedling establishment but has not been compared with traditional seedbed preparation techniques. We compared seedling emergence of broadcast-seeded 'Vaughn' sideoats grams [Bouteloua curtipendula (Michx.) Torr], 'A-130' blue panic (Panicum antidotale Retz.), 'A-68' Lehmann lovegrass (Eragrostis lehmanniana Nees), and 'Cochise' atherstone lovegrass (Eragrostis lehmanniana Nees X E. tricophera Coss and Dur.) on lightly and heavily trampled seedbeds with that on undisturbed, land imprinted, and root-plowed or ripped seedbeds. We seeded and applied the treatments prior to summer rains on a sandy loam soil in southern Arizona for 3 years. In a wet year (1987) when surface soil water was estimated to be available for at least 24 consecutive days, heavy trampling and land imprinting increased emergence of blue panic and land imprinting increased emergence of Cochise lovegrass. In that year, lovegrass emergence was high even on undisturbed plots. In a moderately wet year (1988), surface soil water was available for periods of 6-9 days during seedling emergence and greater disturbance, either by heavy trampling, land imprinting and/or root plowing or ripping produced higher emergence than light trampling and nondisturbance. In a dry year (1989), surface soil water was available for periods of 2-3 days and seedling emergence was low and generally similar for all treatments. Sideoats grama emergence was low all 3 years, but was highest in 1988 when initial thunderstorms were followed closely by subsequent storms. Seedbed disturbance by cattle and mechanical methods may enhance revegetation in the Southwest in years of moderate precipitation but may be unnecessary in wet years or futile in dry years, depending on species and soils.

Grass Seedling Emergence, Morphology, and Establishment as Affected by Planting Depth

AbstractThe seeding depth of grasses affects emergence and adventitious root development. Seedling root morphology and development should be considered when determining planting depth for forage grasses. A field study was conducted on a Kennebec silt loam (fine‐silty, mixed, mesic Cumulic Hapludolls) during June to August 1985 and 1986 to investigate the effect of planting depth on seedling emergence, morphology, and establishment of smooth bromegrass (Bromus inermis Leyss.), big bluestem (Andropogon gerardii var. gerardii Vitman), indiangrass [Sorghastrum nutans (L.) Nash], and switchgrass (Panicum virgatum L.). Seeds were planted by hand to insure seeding depths of 1.5, 3.0, 4.5, and 6.0 cm. Emergence percentage decreased with increased planting depth for all grasses except switchgrass, which had similar percentages at the 1.5‐ and 3.0‐cm planting depths. Coleoptile length and seedling crown depth were positively correlated with actual planting depth in smooth bromegrass, while subcoleoptile internode length was positively correlated with actual planting depth in big bluestem, indiangrass, and switchgrass. Indiangrass differed from big bluestem and switchgrass, since its coleoptile length was positively correlated with actual planting depth. Smooth bromegrass may have the potential of increased adventitious root development due to deep placement of the seedling crown in the soil. Big bluestem, indiangrass, and switchgrass do not have the potential of increased adventitious root development as seeding depth increases, since there was no correlation of seedling crown depth with actual planting depth. Rapid increase in adventitious root number of big bluestem, indiangrass, and switchgrass was noted after three or more consecutive days of rainfall after 4 wk from planting.

Interrelations of the Physical Properties of Coppice Dune and Vesicular Dune Interspace Soils with Grass Seedling Emergence

Interrelations of the Physical Properties of Coppice Dune and Vesicular Dune Interspace Soils with Grass Seedling Emergence

Grass Seedling Emergence and Survival after Treatment with Fungicides

Grass Seedling Emergence and Survival after Treatment with Fungicides

Emergence of Grass Seedlings under Crop Residue Culture

Emergence of Grass Seedlings under Crop Residue Culture

Grass Seedling Emergence and Survival from Furrows

Grass Seedling Emergence and Survival from Furrows

Effect of Soil Bulk Density and Soil Water Pressure on Emergence of Grass Seedlings1

AbstractMoisture was the most important factor influencing the emergence of common bermudagrass (Cynodon dactylon (L.) Pers.) and weeping lovegrass (Eragrostis curvula (Schrad.) Nees.) in a clay soil over the range of bulk density and soil water pressure investigated. Both grasses exhibited approximately the same emergence at the −1/3 and −1‐bar soil water pressures. Of those soil strengths and oxygen diffusion rates encountered, none limited seedling emergence of either grass. Small correlation was found between soil strength and seedling emergence.

The Seedling Emergence of Grasses as Affected by Low Temperature1

SynopsisCold tolerance of the grass seedling decreases with advancing stage of the pre‐emergence period. Reduced tolerance is evidenced both by reduction and delay in emergence. Pre‐emergence cold tolerance may be masked by seedling susceptibility to soil‐borne pathogens if these are not adequately controlled.